Since electrochemical capacitors such as electric double layer capacitors can easily reduce their size and weight, they are expected to become power supplies and backup power supplies for portable devices (small-size electronic devices) and auxiliary power supplies for electric cars and hybrid cars, for example, and various studies have been under way in order to improve their performances.
In particular, for responding to recent demands for reducing the size and weight of portable devices and the like, there have been needs for developing electrochemical capacitors which can further reduce their size and weight so as to be placed in a smaller space while keeping performances required for devices to which the electrochemical capacitors are to be mounted. Namely, electrochemical capacitors are required to improve their energy density per unit mass and per unit volume.
For realizing improved performances and reduced size and weight in electrochemical capacitors, electrodes within the electrochemical capacitors have also been desired to improve performances and reduce their size and weight.
Known as a technique for manufacturing an electrochemical capacitor electrode and electrochemical capacitor intended for improving the electrode characteristics mentioned above is one comprising the steps of shaping a kneaded product composed of an electrolyte powder contained in a nonaqueous electrolytic solution (a solution employed in the electrochemical capacitor), a conductive powder (activated carbon, carbon, or the like), and a binder into a sheet as a shaped article (electrode material), and impregnating this shaped article with an organic solvent of the same species as with the organic solvent contained in the nonaqueous electrolytic solution, so as to inject the nonaqueous electrolytic solution sufficiently into an electrode, thereby reducing the internal resistance and fluctuations in characteristics (see, for example, Japanese Patent Application Laid-Open No. HEI 5-283287 (Claim 2)).